Riboflavin is a novel elicitor of systemic acquired resistance ( SAR ) in plants and activates a distinct defense signaling pathway from several known ones. Here, we analyzed the role of riboflavin in wheat seedlings ( Yangmai 16) defense against powdery mildew (Blumeria graminis f. Sp. Tritici). The effects of fungicidal activity on leaves were detected through the progress of colonies. Riboflavin with different concentrations (0,10,15,25 mol/L) was used respectively. The result showed that foliar application of riboflavin was helpful for wheat to restricting infection of powdery mildew. 3 d after pathogen inoculation,colonies were abruptly increased in control plants; 7 d after pathogen inoculation, colonies in plants with foliar application of riboflavin were also lower than control. However,the plants treated with foliar application of riboflavin showed absolutely defensive symptom. The initial response to foliar application of riboflavin in the leaves was hydrogen peroxide (H2O2) abruption, but there was no significantly difference among concentrations of riboflavin. While riboflavin was used together with CAT (catalase) , the function of riboflavin suppress the infection of powdery mildew in wheat disappeared; suggesting that the role of H2O2 regenerated by riboflavin in priming defenses is necessary.%核黄素是一种植物抗病性激发子,能够激发植物的防御反应使植物对病原菌起到抗性作用.为研究核黄素诱导小麦对白粉菌抗性,利用不同浓度的核黄素(0,5,10,15,25μmol/L)处理小麦幼苗植株,12h后接种白粉菌,结果表明,核黄素处理的小麦幼苗叶片中H2O2短时间内有显著的积累,小麦发病情况与对照相比显著降低.叶片中诱导产生的H2O2量与核黄素的浓度有关,但不同浓度处理诱导植株产生的抗病性没有差异.在喷施核黄素的小麦上接种小麦白粉病菌同时加入H2O2清除剂CAT,核黄素诱导小麦抗病性消失.试验结果表明核黄素能够诱导小麦增强对抵抗白粉病菌的侵染能力,核黄素诱导小麦对白粉病菌的抗性依赖于H2O2.
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